The present invention relates to a ventilated air bellows for a pneumatic spring, a pneumatic spring containing a ventilated air bellows as well as a pneumatic spring system containing ventilated air bellows.
Conventionally, a vehicle axle of a commercial vehicle comprises an axle body which by means of at least one trailing arm forms an axle assembly and therefore is movably hinged on the vehicle frame and supported relative to the vehicle frame by means of a pneumatic spring arranged above or behind the crossing area of the axle body and the trailing arm. The pneumatic spring in turn comprises an air bellows arranged between a top and a base plate, wherein for a mechanical coupling between the air bellows on the one hand and the axle assembly on the other hand there is provided a plunger which is arranged on the air bellows. At its axle-side portion the air bellows is connected to the plunger, wherein an outer surface of the plunger serves as a rolling or unfolding surface for the air bellows so that a guided movement of the air bellows is ensured during operation when the plunger moves up and down.
However, such pneumatic springs are to a limited extent only suitable for crane and train loading since due to the weight of the axle, which will then hang below the vehicle, the air bellows is completely extended or unfolded without further support devices so that a negative pressure is generated in the air bellows relative to its surroundings. When the vehicle is set down, there is the danger that the air bellows folds towards the inside or tilts relative to the plunger or folds in and, hence, does not unroll or unfold along the plunger, as would be normal operation, which might lead to damage.
In order to avoid this problem, conventionally in crane and train loading the range of spring of the pneumatic spring is limited by means of mechanical locking with the help of a tensioning or gripping device attached to the vehicle frame, or a divided plunger is used. Alternatively, the pneumatic spring may also be designed such that the pneumatic spring is releasably connected to the body and, in the case of crane loading of the trailer, is separated from the body by means of a returning device, and by means of the returning device the top, and thus the bellows as well, is held in a defined position relative to the plunger so that the air bellows unrolls or unfolds along the plunger or is held in an unrolled or unfolded state. In addition, also the use of so-called “splitters” is possible, wherein the upper bellows attachment is attached not to the vehicle frame but to a pivoting arm.
The object underlying the invention is to provide an air bellows for a pneumatic spring, a pneumatic spring containing an air bellows as well as a pneumatic spring system containing air bellows, which are in a simple manner suitable for the crane loading of vehicles.